Relationship between vitamin D receptor gene polymorphism and periodontitis

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions. METHODS: Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion. RESULTS: One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.     

Expression of endothelial adhesion molecules in the alveolar ridge mucosa,gingiva and periimplant mucosa

OBJECTIVES: The purpose of this study was to analyze the expression of adhesion molecules on endothelial cells in the alveolar ridge mucosa, the gingiva and the periimplant mucosa in humans. MATERIAL AND METHODS: Twelve partially edentulous subjects were included in the study. In each subject, one soft tissue biopsy was harvested from the edentulous alveolar ridge mucosa, one from a tooth site and one from an implant site. After 3 weeks of undisturbed plaque accumulation, an additional biopsy was obtained from one tooth and one implant site in each subject. The tissue samples were snap frozen and prepared for immunohistochemical analysis. RESULTS: In the alveolar ridge mucosa, smaller proportions of endothelial cells expressing ICAM-1, ELAM-1 and VCAM-1 were observed than in the gingiva. ELAM-1-positive cells occurred in lower numbers than in periimplant mucosa. After 21 days of plaque accumulation, ELAM-1 was increased in tooth sites, but decreased in periimplant mucosa. CONCLUSION: The results of the present study indicated that the proportions of activated endothelial cells and the extravasation of leukocytes is larger in gingiva and periimplant mucosa than in alveolar ridge mucosa. This might be due to the less permeable keratinized epithelial layer in the edentulous ridge mucosa, which offers proper protection against microbial pathogens. The greater expression of endothelial cell adhesion molecules during experimental gingivitis, compared to periimplant mucositis, may reflect its longer history of repeated antigenic assaults.     

The effect of dentine on fluorescence measurements of enamel lesions in vitro

This study aimed to determine the contribution of the underlying dentine and the enamel-dentine junction to measurements of mineral loss from enamel recorded using quantitative light fluorescence (QLF). Sixteen square blocks (5 x 5 mm) were cut from the labial surfaces of extracted bovine incisor teeth. A dental drill was used to remove dentine and the enamel-dentine junction from half of each specimen. All specimens were embedded in epoxy resin and ground to produce a smooth, flat enamel surface. Half of the enamel surface of the block, perpendicular to where the dentine had been removed, was demineralised for 72 h prior to undertaking QLF measurements from the enamel surface to compare fluorescence loss from different areas of the block. QLF readings taken from lesions with no underlying dentine or enamel-dentine junction were very similar to readings from lesions with underlying dentine. A comparison of the two data sets demonstrated a linear relationship with a gradient of 0.95 and a y intercept of -1.24 (r(2) = 0.936). From these data, the underlying dentine and enamel-dentine junction did not influence mineral loss in enamel measured using QLF.     

Traumatic neuroma of the great auricular nerve. A clinical case

A clinical case of neuroma resulting from an amputation which occurred following parotid surgery is reported. The present paper discusses the importance of differential diagnosis relating to this pathology and the surgical techniques that may contribute to setting a limit on its onset. Traumatic neuroma is a possible complication of parotid surgery together with motor deficiencies and Frey's syndrome and the less frequent salivary fistulas. It may also occur following oncological or plastic-reconstructive surgery. During parotidectomy operations, section of the great auricular nerve may be required to facilitate access to the parotid region. This manoeuvre may, however, also be associated with the onset of a neuroma during a time period varying from 2 to 10 years, according to the various authors who have examined the subject. The laterocervical tumefaction associated with neuroma poses a number of diagnostic problems as it has to be differentiated from a likely relapse or possibly from more complex inflammatory or metastatic lymphnodal pathology. A correct clinical and diagnostic multidisciplinary approach is fundamental if the pathology is to be classified in the right way and contributes to alleviating a state of mental unease in the patient that is associated with the sudden appearance of the tumefaction. Sectioning the nervous trunk by means of thermocautery and its subsequent sinking below the main trunk of the sternocleidomastoid muscle, are simple surgical manoeuvres that are useful for preventing the onset of traumatic neuroma.     

Evidence for reactive nitrogen species formation in the gingivomucosal tissue

An increase in nitric oxide production has been demonstrated in periodontitis. Here we investigated the potential role of nitric-oxide-derived nitrating species (such as peroxynitrite) in a rat model of ligature-induced periodontitis. Formation of 3-nitrotyrosine, the stable product formed from tyrosine reacting with nitric-oxide-derived nitrating species, was detected in the gingivomucosal tissue. 3-Nitrotyrosine immunohistochemical analysis revealed a significant elevation in the number of immunopositive leukocytes, and higher immunoreactivity of the gingival ligaments and epithelium in the ligated than in the contralateral (control) side. On both sides, several 3-nitrotyrosine-positive bands and, on the ligated side, a unique 52-kDa 3-nitrotyrosine-positive band were detected by Western blot. However, in the sterile gingivomucosal tissue of rat pups, no 3-nitrotyrosine or inducible nitric oxide synthase immunoreactivity was found. Analysis of these data suggests that resident bacteria of the gingivomucosal tissue induce an increase in reactive nitrogen species, which is greatly enhanced by plaque formation in periodontitis.     

A comparative study of sialic acid-rich proteins in rat bone and dentin

Four sialic acid-rich (SA-rich) proteins found in bone and dentin, osteopontin (OPN), bone sialoprotein (BSP), bone acidic glycoprotein-75 (BAG-75), and dentin matrix protein 1 (DMP1), share some common features. We used SDS-PAGE and Western immunoblots to analyze and compare SA-rich proteins in bone and dentin extracts from rats with a single chromatographic procedure. OPN was detected in dentin extracts, with a relative level less than one-seventieth of that in bone. Both bone and dentin BSP demonstrated an extremely broad distribution pattern, probably due to a high degree of heterogeneity in post-translational modifications. BAG-75 in both bone and dentin was detected as an 83 kDa band, dramatically distinct from that of DMPI. Using a polyclonal antibody raised against a purified bone 57 kDa protein (a portion of DMPI), we detected 150 kDa protein bands in bone fraction; the same bands were recognized by antirecombinant rat DMPI antibody. Bands from dentin migrating at about 150 kDa in earlier fractions and progressing to 200 kDa in later fractions showed a clear immunoreactivity to the anti-57 kDa antibody. We conclude that the majority of DMPI in rat bone is processed into fragments, whereas that in dentin remains intact.     

Effects of cyclosporin A on dental alveolar bone: a histomorphometric study in rats

BACKGROUND: We have previously reported cyclosporin A (CA)-induced osteopenia around the dental alveoli of the mandibular incisors of rats. The drug-induced tooth displacement and the regional anatomical complexity around the mandibular incisors might complicate the local effects of CA. Therefore, the purpose of this study was to evaluate the dental alveolar bone histomorphology around maxillary secondary molars in CA-treated rats and to further elucidate the effects of CA on the dental alveolus. METHODS: Twenty Sprague-Dawley rats were assigned to a CA and a control group. Animals in the CA group received CA (15 mg/kg) daily and the control rats received only mineral oil. At the end of weeks 2 and 4, five animals in each group were sacrificed. Dental alveoli around the maxillary second molar region were frontally sectioned and stained with toluidine blue by undecalcified histological processing. Ten serial tissue sections, 80 microm apart, were selected for histometric evaluation. Bone volume, bone-specific surface, and osteoid formation were measured at buccal, apical, and palatal locations in dental alveolus. RESULTS: Overall bone mass in dental alveolus decreased more in the CA group than in the control group at both observation intervals. All histometric measurements, except the bone-specific surface, were significantly affected by the alveolar location (palatal, apical, and buccal) and CA therapy (P= 0.004 and <0.001, 0.001 and <0.001, 0.004 and <0.001 for drug therapy and location of the dental alveolus in bone volume, marrow volume, and the ratio of bone surface to volume, respectively). Decreased bone volume, but increased marrow volume, were noted in the CA group compared to the control group. Although the alveolar bone surface area did not differ between the CA group and the control group, greater alveolar surface-to-volume ratio was noted in the CA group. For osteoid, more decreased volume, seam width, and fractional formation surface were observed in the CA group compared to the control group (P <0.001, <0.001, and = 0.046 in osteoid volume, seam width volume, and formation surface, respectively). CONCLUSIONS: Because the bone mass and the osteoid formation in the dental alveolus around the maxillary molar region showed a decrease after CA exposure, we conclude that this drug has inhibitory effects on the dental alveoli.     

Harmonic analysis of facial profiles: a 10-year evaluation

A 10-year longitudinal evaluation was performed of the morphology of soft tissue facial profiles of 14 healthy adults (8 female and 6 male; mean age at the second evaluation, 34 years). Standardized left-side photographs were taken of each subject, and facial profiles were traced between trichion and cervical point. The line joining the 2 landmarks was set as the baseline, and each outline was automatically digitized and mathematically reconstructed by a 20-harmonic elliptic Fourier series expansion. Shape modifications were quantified by calculating the morphologic distance between the Fourier reconstruction of each facial profile in the 2 examinations. The area enclosed in each facial outline was automatically computed, and the difference between the soft tissue areas obtained in the 2 examinations was calculated. On average, significant longitudinal differences were found in both men and women for shape differences (P < 0.05), while size variations were significant only in men. While the 10-year increase in size was significantly (P < 0.01) larger in men than in women, no sex-related differences were found for shape modifications. Between the third and the fourth decades of life, both men and women experience some modifications in their facial soft tissues. While shape changes in both sexes, size changes are particularly evident in men and less manifest in women, who show greater variability in the amount of change that takes place.